Home > Encyclopedia of Science > LED (Light-Emitting Diode)

• Words to Know
• Convenient uses

An LED, or light-emitting diode, is a special type of diode that emits light when connected in a circuit. A diode is an electronic device that has two electrodes arranged in such a manner as to allow electrical current to flow in one direction only. With its ability to control the flow of electrons, a diode is often used as a rectifier, which is a device that converts alternating current into direct current. Alternating current is an electric current that flows first in one direction and then in the other. Since alternating current fed into a diode can move in one direction only, the diode converts the current to a one-way flow known as a direct current.

An LED converts electrical energy to light by means of a semiconductor, a substance that conducts an electric current, but only very poorly. A semiconductor for an LED...